Is air flotation generally effective for treating steel mill wastewater?
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Personally, I think the effect is not good; it’s not as good as the water that comes out after sedimentation. If a coagulant is also used in air flotation, what impact does that have? The manufacturer’s equipment has already been installed; it’s not feasible to avoid using it, haha. It’s difficult. If there are people from the manufacturer involved, it would be advisable to consider integrating the equipment with the actual water treatment process. The equipment manufacturer and the water treatment company could work together to determine the appropriate treatment procedures
Steel rolling wastewater mainly requires oil removal, and air flotation works well for this purpose. If it is used to remove suspended solids from steel rolling wastewater, its effectiveness is inferior to that of natural sedimentation.
What if a flocculant is added before air flotation? Hehe, from my experience, if air flotation is used, it should be done before flocculation and sedimentation. In my opinion, there is no need to use air flotation, and the requirements for reusing steel-making wastewater are not high (secondary cooling water, which is used in steelmaking, is excluded). Generally, steel plants rarely use air flotation; the results I’ve seen have been poor, as flocculation and sedimentation are the methods that actually work. Chemical degreasers or inclined plate sedimentators (with attached skimming machines) can handle both oil and suspended particles (by adding flocculants)
Flotation itself is a process for separating flocs from liquid; the difference is that in coagulation sedimentation, the sludge sinks to the bottom, while in flotation, the scum remains on the surface of the water. Air flotation is highly effective for oil removal in steel mills; it is also used to some extent in the turbulent circulation systems of steel mills, where it yields good results as well. Currently, many steel mills require water reuse, such as through clean circulation and turbid circulation systems. It is entirely possible to reuse a portion of the treated wastewater in the turbid circulation system; this not only saves water resources but also allows the plants to claim zero wastewater discharge.
Flocculation is required in air flotation processes, right? As for comparing it with coagulation-sedimentation, I think it depends on the quality of the inlet and outlet water as well as the specific process used; there’s no universal rule that applies in all cases. :)